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Imaging with the 130pds


Russe

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Cheers Roland I'm cooling with a peltier:

The sensor was stable at -5c. The image is still noisy because I was using high gain 30s subs and you generally need a lot more subs using that method. Unfortunately it was quite windy as well so longer exposures were out. Hopefully I'll get better results in calmer weather.

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39 minutes ago, cuivenion said:

Cheers Roland I'm cooling with a peltier:

The sensor was stable at -5c. The image is still noisy because I was using high gain 30s subs and you generally need a lot more subs using that method. Unfortunately it was quite windy as well so longer exposures were out. Hopefully I'll get better results in calmer weather.

Mate!
Your cooling system is much more impresive than the image of M51!!!!!!!!!!!!! :)
Wow

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Hi again once more time...
While playing around with the drawtube cap and Dark subs during a daytime I have diagnosed one disturbing hole in the scope...

I wonder if everyone has it in the same place.... I flocked mine and I afraid I placed primary incorrectly.

IMG_20200509_193412.thumb.jpg.8240ff55f2be828d035deabe048e2a11.jpgIMG_20200509_193405_1.thumb.jpg.71ddeddb917d4b768f217546f1985f24.jpgIMG_20200509_193541.thumb.jpg.e751a7a1690338f10a885ee89ceddd7d.jpg

And usual temp solution which I don't like.... :)

IMG_20200509_194041.thumb.jpg.71f3613c52978ad52d3483d088bb6e9c.jpg

 

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19 hours ago, Knight of Clear Skies said:

Excellent thanks, added to basket. Always good to have a recommendation rather than taking a punt.

When it turns up, you will notice it has a grid pattern on the illuminated side. That will disappear once you put a few sheets of A4 on it - you probably need about 3 or 4 sheets to dim it sufficiently enough for lum flats on its lowest setting. For narrowband just hit the power key once or twice to increase the brightness (you have three levels). It runs fine for ages from a small powerbank

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3 hours ago, Uranium235 said:

When it turns up, you will notice it has a grid pattern on the illuminated side. That will disappear once you put a few sheets of A4 on it - you probably need about 3 or 4 sheets to dim it sufficiently enough for lum flats on its lowest setting. For narrowband just hit the power key once or twice to increase the brightness (you have three levels). It runs fine for ages from a small powerbank

I used to use a single sheet of A4, but discovered that flats with an uncovered board work just as well because it is so far out of focus.

But I've noticed my habit of rotating the panel has created circular scratches that have created a bright ring so I'm going back to a single sheet of A4 chiefly as a protector.

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10 hours ago, Stub Mandrel said:

I used to use a single sheet of A4, but discovered that flats with an uncovered board work just as well because it is so far out of focus.

 

Depends on whether your camera has a shutter or not. The QSI does (as is usual for KAF8300), so I usually give it at least 3 seconds per flat - hence the need to dim sufficiently :)

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I'm using a heavier camera than I used to with my 130pds and found I needed to really tighten the focus stop screw. Unfortunately that introduces tilt. I've tried adjusting the tension so I don't need to use the focuser stop, that introduces tilt too.

My plan is to tension as much as possible and then re adjust the focuser so the tilt is gone. Does that seem viable? I'm not used to focuser adjustment so I thought this thread would be a good place to get a few opinions.

Edited by cuivenion
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I have just finished making a 130 pds!  My very first scope was an Orion Space Probe 130 ST which I have been told are made by Skywatcher and compares directly to there own model which maybe a 130P ?

A while back I thought it would be a great idea to put my Nikon DSLR on it only to find the horrible 1.25 plastic focuser is just no good.

I bought a two inch pds focuser from FLO, modded the tube, flocked it and blackened the mirror edges. With my alternative 130 pds I was ready for AP! Hang on a minute still no good as I do not have enough back focus.

I have now moved the primary mirror a small amount towards the secondary by using longer colimation studs and mirror bolts and the camera now gains focus.

The weather has been rubbish for a while now so I have only tested it on a very distant object in daylight. The question is ‘Am I a legit member of the 130 pds club?’ If it helps at all I have a 150 pds as well.

Marv

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Hi everyone,

I'm reading this topic since a few months and I finally decided to join the discussion :)

I have had a 130PDS for a few months now and did most of the modifications that were discussed here. But I always had a tilt anywhere in my system, so I eventually found out that the focuser was causing it.

So I bought a Monorail focuser from Teleskop-Service (here in germany), as they are pretty good for the money. Only problem is, there is no baseplate available to put it on the 130PDS. So in about 3 weeks I'll get a custom baseplate out of aluminum (that costs me about 130€) that I designed myself. If any of you want's to do the same, just tell me and I'll send you the CAD model / plans.

As soon as I get it, I'll post some pics of it here.

Anyway, apart from the tilt I'm quite happy with my 130PDS. I could take only 3 images with it for now, but I love them:

V1_MitRahmen_800p.png

M31_800p.png

V1_final_rahmen_800p.png

All images are taken with a QHY294c at standard gain 1087. I used no bias, but flat-darks instead. More details can be found at my astrobin account:

https://www.astrobin.com/users/TheCounter/

There is still much room for improvement :)

Greetings from germany

Kevin

Edited by TheCounter
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Lovely pics Kevin.

Unfortunately it seems almost no-one is aware there are three grub screws around the base of the  Skywatcher focuser, you can loosen the fixing screws and adjust the grub screws to change the tilt.

 

Edited by Stub Mandrel
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1 hour ago, Stub Mandrel said:

Lovely pics Kevin.

Unfortunately it seems almost no-one is aware there are three grub screws around the base of the  Skywatcher focuser, you can loosen the fixing screws and adjust the grub screws to change the tilt.

 

Thank you.

About the focuser, I actually know about these adjustment screws, but thats not the problem. The focuser tube does flex a bit from the weight of the camera.

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Here's my first light with my new modded 600D on the Elephants Trunk Nebula.

I took 22x600s @ 1600ISO with a Duo Narrowband filter.

I decided not to take any darks as this would waste heaps of time, and just decided to dither at 5 on APT but I can still see some questionable banding? I took flats and used my superbias as a master dark.

I definitely need more data as it's very noisy but at least it's a start and when it's next clear I can take more subs. Is 10 minutes too long especially for a non cooled DSLR?

Also what's the best way to mitigate the red stars?

Image35.jpg

Edited by matt_baker
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Gone at it again. Forgot that with canon banding you have to rotate the image 90 degrees before applying the reduction. Went for a more subtle approach and made sure DBE was correct unlike last time

Also seems to be an artefact that didn't get corrected by my flats toward the bottom left. I exposed for almost half well depth and that ended up being about 75% of the histogram, so I'm not sure if the flats were too bright to pick up the dust?

HOO v2.jpg

Edited by matt_baker
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On 28/04/2020 at 22:48, matt_baker said:

Do you have a before and after comparison with your flats? I'm considering doing this based on your idea and it looks cheap and effective, without spending £200 on a flatbox.

Would rather spend that money on going towards a mono cam rather than that

Here is the (stretched) master flat taken with that panel, looks fairly normal... apart from the excessive amount of motes...lol

MasterFlat_ISO0.thumb.jpg.d985a92a96930fec26106504eb262540.jpg

 

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5 hours ago, matt_baker said:

Also what's the best way to mitigate the red stars?

 

By killing all star colour in Ps:

 

Filter > Noise > Reduce noise

Strength: 10

Preserve detail: 10

Colour noise reduction: 10

Sharpening: 0

 

You can either apply that to the whole image, or on a star selection only.

 

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On 13/05/2020 at 08:44, TheCounter said:

Hi everyone,

I'm reading this topic since a few months and I finally decided to join the discussion :)

I have had a 130PDS for a few months now and did most of the modifications that were discussed here. But I always had a tilt anywhere in my system, so I eventually found out that the focuser was causing it.

So I bought a Monorail focuser from Teleskop-Service (here in germany), as they are pretty good for the money. Only problem is, there is no baseplate available to put it on the 130PDS. So in about 3 weeks I'll get a custom baseplate out of aluminum (that costs me about 130€) that I designed myself. If any of you want's to do the same, just tell me and I'll send you the CAD model / plans.

As soon as I get it, I'll post some pics of it here.

Anyway, apart from the tilt I'm quite happy with my 130PDS. I could take only 3 images with it for now, but I love them:

V1_MitRahmen_800p.png

M31_800p.png

V1_final_rahmen_800p.png

All images are taken with a QHY294c at standard gain 1087. I used no bias, but flat-darks instead. More details can be found at my astrobin account:

https://www.astrobin.com/users/TheCounter/

There is still much room for improvement :)

Greetings from germany

Kevin

Astonishing photos...

I had the same issue with a 200pds, great replacement focuser - rubbish baseplate. So I designed my own as you did, but I had it 3D printed instead.

When designing, have a think about how it will all attach to the tube. Might be worth uprating the bolts to M5, and where the nut goes on the inside - a flexible placstic washer or something simlilar to spead the contact area of the nut out a bit more (flat nut on a curved surface is never good).

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Okay, so I've added 3 hours more data but now I'm getting what looks like walking noise in the image and I don't understand why. I'm dithering on the max setting in APT which is 5 with PHD 2 guiding. I did notice when it did dither that my graph didn't actually seem to move when the dither command was sent on some of the frames. Maybe some of them didn't actually dither properly when it was supposed to?

HOO_DBE_clone.jpg

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30 minutes ago, Dan13 said:

not sure if im in the wrong place to post this but has anyone used this with the 130pds? 

https://www.rothervalleyoptics.co.uk/baader-mpcc-multi-purpose-coma-corrector-mark-iii.html

Plenty of folks. Consensus seems to be that the Baader has better control of reflections of very bright stars, but is fussy about spacing - the Skywatcher is fit and forget.

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